Tamper evident tape with integrated emi shielding

ABSTRACT

The present invention provides a multilayer tape for simultaneously providing shielding of electromagnetic interference (EMI) and evidence of tampering with an electronic device to which it is applied. The multilayer tape can be attached to an electronic device to cover a seam or other opening in the electronic device. An embossed surface provides evidence of the disruption of the tape, and the tape includes a conductive adhesive to provide EMI shielding. The multilayer tape is particularly useful for sealing the seams of a disk drive device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional PatentApplication Ser. No. 60/772,333, filed on Feb. 10, 2006, the disclosureof which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to the field of electronic devices and inparticular relates to an adhesive tape that combines the functionalityof electromagnetic interference (EMI) shielding with tamper detection.The tape is particularly useful to provide tamper detection and EMIshielding for electronic components such as disk drives for the storageof data.

BACKGROUND

Security devices in the form of a multilayer tape that is adhered to theseam of an enclosure, such as a DVD case or an enclosure for electroniccomponents, have been used where the tape includes a hologram ordiffraction grating. When attempts to open the enclosure occur, thestructure of the tape is disrupted and the image or pattern on the tapeshows evidence of the attempt.

EMI shielding devices such as EMI shielding tapes are also known. EMIshielding tapes can be used to prevent electromagnetic interferencebetween different components of an electronic device. Increasing devicefrequencies create decreasing electromagnetic wavelengths that canpenetrate very small cracks or openings that may exist in an enclosuresurrounding the electronic components. Device failures caused by EMI areincreasing as the electronic components become more sensitive. Suchtapes can be applied to seams, slots or gaps on the device to reduce EMIby creating a Faraday Cage around the electric components.

Recently, magnetic disk drives for the storage of data have beensignificantly reduced in size and have found use in myriad devices suchas cellular telephones and personal digital assistance (PDAs). In suchdevices, the electromagnetic interference caused by operation of thedisk drive can significantly affect the performance of the device. Atthe same time, disk drive manufacturers also desire to inhibit usersfrom tampering with the device and then making false warranty claims.

SUMMARY OF THE INVENTION

According to one embodiment of the present invention, a multilayer tapethat is adapted to provide evidence of tampering and also provideelectromagnetic shielding is provided. The tape includes a substratehaving first and second opposed surfaces where the first surface is anembossed surface. An electrically conductive material layer is disposedover the embossed surface and an electrically conductive adhesive layeris disposed on the conductive layer. The tape can advantageously beapplied to an electronic device such as a disk drive by adhering theadhesive layer to the surface of the device. By virtue of theelectrically conductive adhesive layer and the electrically conductivematerial layer, the tape advantageously provides EMI shielding when thetape is applied over a gap or seam in the device enclosure. In addition,the embossed surface can provide evidence of tampering with theelectronic device when someone attempts to open the enclosure.

According to another embodiment, a disk drive device is provided thatincludes a base plate, a cover connected to the base plate to define anenclosure for housing disk drive components, and a multilayer tape thatcovers at least a portion of a seam between the base plate and thecover. The multilayer tape includes a security layer adapted to indicateif the base plate and cover have been disconnected, a conductivemetallic layer disposed between the security layer and the seam and anelectrically conductive adhesive disposed between the conductivemetallic layer and the seam. The seam can be disposed around theperimeter of the disk drive device and the multilayer tape preferablycovers substantially the entire seam, providing a continuous electricalconnection between the cover and the base plate.

According to another embodiment of the present invention, a method forthe manufacture of a multilayer tape structure is provided. The methodincludes the steps of providing a polymer substrate having first andsecond opposed surfaces, embossing the first surface to form an embossedsurface, depositing a metallic layer onto the embossed surface anddepositing a conductive adhesive onto the metallic layer.

DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross-sectional view of a multilayer tape accordingto an embodiment of the present invention.

FIG. 2 illustrates a disk drive device.

FIG. 3 illustrates a perspective view of an assembled disk drive device.

FIG. 4 illustrates a perspective view of an assembled disk drive deviceincluding a multilayer tape according to the present invention.

DESCRIPTION OF THE INVENTION

A cross-sectional view of a multilayer tape 100 according to the presentinvention is illustrated in FIG. 1. The tape 100 includes a substrate102 upon which an embossed surface 104 is formed to create a securitylayer. An electrically conductive material layer 106 is disposed on theembossed surface 104 and a conductive adhesive layer 108 is disposed onthe conductive material layer 106. In use, the tape 100 is adhered to anelectronic device by virtue of the adhesive layer 108. When adhered tothe seam of an enclosure that surrounds the electronic device, themultilayer tape 100 advantageously provides EMI shielding and alsodeters unauthorized users from opening the enclosure.

The substrate 102 is preferably an organic polymer, for example, apolyester such as polyethylene terephthalate (PET), polypropylene,polyvinyl chloride, polyethylene naphthalate, polymethylpentene (PMP) orpolyimide. The substrate should be sufficiently thin such that thesubstrate 102 is not opaque, thereby permitting the embossed layer 104to be viewed when observed through the substrate 102. In one embodiment,the substrate 102 has a thickness of at least about 10 μm and notgreater than about 30 μm.

An embossed surface 104 is formed on one of the two opposed surfaces ofthe substrate 102. An embossed surface 104 is one that includesstructural discontinuities sufficient to create an optically variablesurface that can be readily observed by a viewer. Thus, when the tape100 is viewed through the substrate 102, the viewer will see the patterncorresponding to the embossed surface 104. The embossed surface 104 canbe formed by etching the substrate 102, such as by a laser or otherapplication of heat.

Deposited on the embossed surface 104 on the opposite side of thesubstrate 102 is an electrically conductive material layer 106. Theelectrically conductive material layer 106 can include any electricallyconductive and optically reflective material. In one embodiment, theconductive material layer is a metallic layer, such as one thatcomprises aluminum. The conductive material layer 106 should besufficiently thick to coat the entire embossed surface 104, butpreferably has a thickness that is less than the thickness of thesubstrate 102. Preferably, the conductive material layer 106 has anaverage thickness of not greater than about 10 μm and more preferablynot greater than about 6 μm. The conductive material layer 106 can bedeposited by vapor deposition of a metal.

An electrically conductive adhesive layer 108 is disposed on theconductive material layer 106. The conductive adhesive layer 108 issufficiently electronically conductive to provide electrical conductancebetween the electronic device to be fitted with the multilayer tape 100and the conductive material layer 106, thereby providing EMI shieldingto the electronic device. According to one embodiment, the conductiveadhesive layer 108 has an electrical resistance of not greater thanabout 10⁻³Ω. Preferably, the electrical resistance of the conductiveadhesive layer is not greater than about 10⁻⁶Ω and even more preferablyis not greater than about 10⁻⁹Ω. The adhesive is preferably apressure-sensitive adhesive so that the tape 100 can be applied to anelectronic device using only pressure. The conductive adhesive caninclude an adhesive matrix and a solid electrically conductive material110 dispersed within the adhesive matrix. For example, the solidconductive material can be selected from the group consisting of carbon,aluminum and nickel. In one preferred embodiment, the solid conductivematerial includes fibers, such as nickel fibers. Nickel fibers arebelieved to be advantageous in this application as the electronicconductance of adhesives containing nickel fibers is less sensitive toapplication pressure than other materials.

The tamper evident tape 100 can be applied to an electronic device overthe seam that is formed between two portions of the enclosure of theelectronic device. By way of example, FIG. 2 illustrates a disk drive210. The disk drive 210 generally includes a base plate 212 and a cover(not shown) that may be disposed on the base plate 212 to define anenclosed housing or space for the various disk drive components. Thedisk drive 210 includes one or more data storage disks 214 of anyappropriate computer-readable data storage media. Each disk 214 ismounted on a hub or spindle 216, which in turn is rotatablyinterconnected with the disk drive base plate 212 and/or cover. Multipledata storage disks 214 are typically mounted in vertically spaced andparallel relation on the spindle 216. Rotation of the disk(s) 214 isprovided by a spindle motor 218 that is coupled to the spindle 216 tosimultaneously spin the data storage disk(s) 214 at an appropriate rate.

FIG. 3 illustrates a perspective view of an assembled disk driveassembly 300. The disk drive assembly includes a base plate 312 and acover 314. The cover 314 is connected to the base plate 312 utilizingthreaded fasteners 316 or a similar mechanism to form an enclosure forthe disk drive components, as is discussed above. Around the peripheryof the disk drive device 300 is a seam 318 that is formed where thecover 314 contacts the base plate 312. Although the seam 318 isreasonably narrow, EMI, such as that produced by operation of the diskdrive motor, is capable of leaking through the seam 318. This EMI caninterfere with the operation of other electrical components that aredisposed in close proximity to the disk drive 300.

FIG. 4 illustrates a disk drive device 300 that includes a multilayertape 320 of the present invention disposed around the seam 318 of thedisk drive device. When the conductive adhesive is a pressure sensitiveadhesive, sufficient pressure should be applied to ensure anelectrically conductive pathway is formed between the enclosure surfaceand the conductive material layer of the multilayer tape 320. Themultilayer tape 320 preferably covers the entire seam 318 to prevent EMIfrom leaking out of the enclosure.

The tape 320 also provides evidence of tampering, i.e., evidence thatthe cover 314 has been removed from the base plate 312. Three interfacesexist after the multilayer tape is applied to an enclosure, namely thesubstrate-conductive material interface, the conductivematerial-adhesive interface, and the adhesive-enclosure interface. Themultilayer tape of the present invention is designed so that theadhesive strength of the substrate-conductive material interface is thelowest. To open the device and access the internal components, the tapemust first be removed from the seam. When a user attempts to remove themultilayer tape, the substrate is peeled away from the underlyingconductive material layer, providing evidence of the tampering. Theadhesive and conductive material layers remain intact and advantageouslycontinue to provide EMI shielding.

While various embodiments of the present invention have been describedin detail, it is apparent that modifications and adaptations of thoseembodiments will occur to those skilled in the art. However, is to beexpressly understood that such modifications and adaptations are withinthe spirit and scope of the present invention.

1-12. (canceled)
 13. A disk drive device, comprising: a base plate; atop cover connected to said base plate and defining an enclosure forhousing disk drive components; and a multilayer tape covering at least aportion of a seam between said base plate and said top cover, whereinsaid multilayer tape comprises: a security layer adapted to indicate ifsaid base plate and said top cover have been disconnected; anelectrically conductive metallic layer disposed between said securitylayer and said seam; and an electrically conductive adhesive disposedbetween said conductive metallic layer and said seam.
 14. A disk drivedevice as recited in claim 13, wherein said multilayer tape coverssubstantially all of said seam.
 15. A disk drive device as recited inclaim 13, wherein said security layer comprises an organic polymersubstrate comprising an embossed surface.
 16. A disk drive device asrecited in claim 13, wherein said conductive metallic layer comprisesaluminum.
 17. A disk drive device as recited in claim 13, wherein saidconductive adhesive has a resistance of not greater than about 10⁻⁶Ω.18-20. (canceled)